WSJT-X: updated virtual device how-to

WSJT-X.md

@@ -33,6 +33,8 @@ You can change the sample rate later in SDRangel audio preferences:
   1. Select the device in the list
   2. Change the sample rate
   
+You will select the virtual device similarly to selecting the default device by right clicking on the "audio mute" button of the SSB demodulator.
+  
 Similarly to the default audio device you can select the "monitor" device that corresponds to the virtual device in WSJT-X preferences:
 
 [[/images/audio/wsjtx_audio_6.png|WSJT-X settings]]